Tethered tow body, communications apparatus and system

ABSTRACT

The problem of providing a submerged vehicle with above-the-surface communications to a nearby vessel, shore platform, or satellite while traveling at operating speed is solved by an efficiently deployable tethered tow body having a hydrodynamic and buoyant hull body and incorporating a lift-generating wing that provides hydrodynamic lift to efficiently lift the tow body containing antennas and other communications devices to the surface. The tow body allows for stable operation during underwater tow, surface tow, and transitions between underwater tow and surface tow. Disclosed embodiments include communications apparatuses encompassing the principles of the tethered tow body, as well as various underwater systems that incorporate a tethered tow body or communications apparatus for establishing communications with a nearby vessel, shore platform, or satellite.

FIELD OF THE INVENTION

The invention relates generally to communications apparatuses, and inparticular to a tethered communications apparatus that providessubmerged vehicles with communications to the outside world.

BACKGROUND

Submerged vehicles, such as unmanned underwater vehicles (UUVs), areused in a variety of military applications, for example, surveillance,reconnaissance, navigation, and defense. When these vehicles aresubmerged, however, navigation and communication are difficult. Inertialnavigation systems, such as gyroscopes or other computer and motionsensors that track position, orientation and velocity can be used, butthese systems are subject to drift the longer they remain below thewater surface. Highly accurate global positioning system (GPS)navigation systems and high-bandwidth radio frequency (RF)communications links are not directly available to submerged vehiclesdue to the rapid attenuation of radio frequency energy by water. Thus,submerged vehicles are limited to communicating with low bandwidthacoustics or wiring back to another vessel or shore platform.

Prior art communications devices for submerged vehicles, such as thedevice disclosed in U.S. Pat. No. 5,379,034, rely primarily on buoyancyto float an antenna to the water surface. The tow angle β of a tetheredcable, calculated as the angle between the cable and the direction thesubmerged vehicle is traveling, is affected by the speed of thesubmerged vehicle. The faster the vehicle travels, the smaller the towangle β, resulting in the tethered cable being pulled straight back andthe communications device never reaching the water surface. The slowerthe submerged vehicle travels, the larger the tow angle β, resulting inthe tethered cable drifting straight up and the communications devicedrifting to the surface. Prior art devices that rely primarily onbuoyancy require the submerged vehicle to be stationary or to betraveling at significantly reduced speed in, order for the antenna todrift to the surface. Thus, submerged vehicles using these prior artdevices cannot simultaneously communicate and travel at operationalspeed. Other prior art systems, such as those disclosed in U.S. Pat.Nos. 3,972,046 and 7,448,339, rely on an intermediary float tethered toan underwater vehicle and a surface float having an antenna. These priorart systems operate at very limited speed ranges because the surfacefloats would be pulled underwater at all but the slowest speeds.Additionally, the intermediary floats of these prior art systems aretowed underwater, thereby increasing the probability of entanglement anddrag when deployed. Still other prior art arrangements, including theantenna arrangement disclosed in U.S. Pat. No. 6,058,874, do not providefor conformal stowage in which a tethered communications device can bestowed within and be quickly deployed from an underwater vehicle,thereby, minimizing drag and the likelihood of vehicle entanglementduring operation.

Accordingly, there is a need and desire for an efficiently deployabletethered communications apparatus and system for providing submergedvehicles with bi-directional, high data rate communications to a nearbyvessel or shore platform as well as GPS coordinate data for precisenavigation while traveling at operational speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a UUV system in accordance with an embodimentdescribed herein.

FIG. 2 is a diagram of a communications apparatus in accordance with anembodiment described herein.

FIG. 3 is a partial internal view of a communications apparatus inaccordance with an embodiment described herein.

FIGS. 4A and 4B are respectively a front view diagram and a bottom viewdiagram of a tow body in accordance with an embodiment described herein.

FIGS. 5A and 5B are respectively a front view diagram and a bottom viewdiagram of a tow body in accordance with another embodiment describedherein.

FIG. 6 is a schematic diagram of an electronics assembly of acommunications apparatus in accordance with an embodiment describedherein.

FIG. 7A is a diagram of a reeling assembly in accordance with anembodiment described herein.

FIG. 7B is a diagram of a reeling assembly mounted inside a UUV systemin accordance with an embodiment described herein.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof and illustrate specificembodiments that may be practiced. In the drawings, like referencenumerals describe substantially similar components throughout theseveral views. These embodiments are described in sufficient detail toenable those skilled in the art to practice them, and it is to beunderstood that structural and logical changes may be made. Sequences ofsteps are not limited to those set forth herein and may be changed orreordered, with the exception of steps necessarily occurring in acertain order.

The problem of providing a submerged vehicle with above-the-surfacecommunications to a nearby vessel, shore platform, or satellite whiletraveling at operating speed is solved by an efficiently deployabletethered tow body having a hydrodynamic and buoyant hull body andincorporating a lift-generating wing that provides hydrodynamic lift toefficiently lift the tow body containing antennas and othercommunications devices to the surface. The tow body allows for stableoperation during underwater tow, surface tow, and transitions betweenunderwater tow and surface tow.

Disclosed embodiments include communications apparatuses encompassingthe principles of the tethered tow body, as well as various underwatersystems that incorporate a tethered tow body or communications apparatusfor establishing communications with a nearby vessel, shore platform, orsatellite.

The invention may be used to particular advantage in the context ofsubmerged vehicles. Therefore, the following example embodiments aredisclosed in the context of UUV systems. However, it will be appreciatedthat those skilled in the art will be able to incorporate the inventioninto numerous other alternative systems that, while not shown ordescribed herein, embody the principles of the invention.

FIG. 1 shows an underwater vehicle system 100 in accordance with anembodiment described herein. UUV 170 may be, for example, a modified ANTGlider Eyak 01 developed by Alaska Native Technologies, LLC or amodified Remus 600 developed by Hydroid, Inc. UUV 170 is modified tointegrate with a communications apparatus 110 having a tether 130connected on one end to a reeling assembly 150 within UUV 170 and on theother end to tow body 120. UUV 170 has propulsor 180 at the aft end anda tow body stowage area 160 cut out on the top surface of UUV 170. Thetow body stowage area 160 has a length and width equal to the length andwidth of tow body 120, and a depth sufficient for tow body 120 to fitentirely within UUV 170.

In accordance with an advantageous feature of this disclosed embodiment,tow body 120 is deployed from the tow body stowage area 160 of UUV 170,thus, enabling UUV 170 to repeatedly establish communications with theoutside world in a quick and efficient manner. Communications apparatus110, comprising hydrodynamic tow body 120 and tether 130 connecting towbody 120 to reeling assembly 150, can be completely stowed inside thetow body stowage area 160 to achieve seamless integration within UUV170. Communications apparatus 110 is positively buoyant enabling it tofloat to the surface using hydrostatic force when UUV 170 is stationary.If desired, vehicle guidance docking plates can be installed in the towbody stowage area 160 to help align tow body 120 inside UUV 170.Seamless integration of communications apparatus 110 has the effect ofminimizing drag and minimizing the possibility of entanglement as UUV170 moves underwater. The communications apparatus 110 and reelingassembly 150 are made so that they are collectively neutrally buoyantand, therefore, will not impact the depth control of UUV 170 when stowedor deployed.

The present inventors have discovered that tow bodies that combine alift-generating wing and a stable body structure achieve goodhydrodynamic performance. Therefore, in accordance with the embodimentsdescribed herein, tow body 120 has a lifting wing mounted on top of atow body structure and, optionally, at least one side float arranged oneither side of the body structure for providing buoyancy at the outeredges of lifting wing and to stabilize tow body 120 during underwatertow.

In accordance with an advantageous feature of the disclosed embodiment,tow body 120 is hydrodynamically clean in that it is designed tominimize drag during underwater tow, to achieve good hydrodynamicperformance during surface tow, and to transition stably betweenunderwater tow and surface tow. Tow body 120 is able to smoothlytransition from underwater tow to being towed at least partially abovethe surface during communication. Additionally, tow body 120 is able tosmoothly transition from surface tow to being towed below the surfaceduring retrieval.

FIG. 2 is a diagram of a communications apparatus 110 in accordance withan embodiment described herein. Communications apparatus 110 has ahydrodynamic tow body 120 with a mounted antenna 250 and a tether 130attaching tow body 120 to reeling assembly 150. Tether 130 is comprisedof tow cable 230 and bridles 270.

In the example embodiment of FIG. 2, tow body structure 210 ismulti-sectional with an elongated center hull body 235, an aft section240 and a fore section 245. Bulkheads are optionally placed at both endsof center hull body 235 to separate center hull body 235 from aftsection 240 and fore section 245.

Lifting wing 200 is mounted on top of center hull body 235 to providehydrodynamic lift for lifting an underwater tow body 120 to at leastpartially above the water surface. Lifting wing 200 is at least as longas the length of tow body structure 210 and is wider than the width oftow body structure 210, preferably, not greater than its length. Thewidth of lifting wing 200, however, is constrained by the width of UUV170. According to the example embodiment of FIG. 2, lifting wing 200curves outward, forming a convex surface. Preferably, lifting wing 200also has a convex fore end, which reduces drag as tow body 120 is pulledthrough water.

According to the example embodiment of FIG. 2, center hull body 235 hasa cylindrical shape while the aft section 240 and fore section 245 arecone shaped. Aft section 240 and fore section 245 of tow body structure210 have convex surfaces and are seamlessly integrated with center hullbody 235. Preferably, aft section 240 is slightly longer than foresection 245. Vent holes 260 are used for cooling an electronics assemblylocated inside the center hull body 235.

Tow body structure 210 of the disclosed embodiment is made ofpolycarbonate, however, tow body structure 210 can be made of any othernon-metallic material having positive buoyancy, such as, for example,carbonfiber, plastic, and fiberglass. The outer hull of tow bodystructure 210 is preferably coated with a fiberglass resin or polyestercoating to provide a low drag surface.

Vertical stabilizer 255 extends from the bottom of tow body structure210, preferably the bottom of aft cone 240, to keep tow body 120substantially parallel with the water surface. If desired, verticalstabilizer 255 is mounted to tow body structure 210 through a keel slot265 built on the underside of aft cone 240. In an advantageous featureof this embodiment, vertical stabilizer 255 is retractable duringstowage to minimize the size of tow body stowage area 160 within UUV170. Vertical stabilizer 255 can be made retractable using a spring ortether 130 can be used to extend vertical stabilizer 255 duringdeployment of tow body 120. Upon retrieval, vertical stabilizer 255 willbe forced inside aft cone 240 by the rear edge of tow body stowage area160.

According to the example embodiment of FIG. 2, communications apparatus110 can provide UUV 170 with high-bandwidth RF communications link andGPS coordinate data. Antenna 250 is a 802.11 antenna providingbi-directional, high speed data rate of at least 1 Mbps at a distance ofat least 1 km. Antenna 250 is preferably small for taking up the leastamount of space in UUV 170 and for being less likely to be noticed whendeployed above the surface. Antenna 250 should also be omnidirectionalto allow it to change position relative to a remote receiver.

Antenna 250 should be as vertical as possible during surface tow so asto provide optimum communications to a nearby vessel or shore platform.In the disclosed embodiment, antenna 250 is spring mounted to liftingwing 200 to keep antenna 250 substantially upright during surface tow.Antenna 250 is preferably positioned to pivot slightly to the rear oftow body 120 to reduce the possibility of breakage if tow body 120encounters an obstacle during tow. According to another advantageousfeature of this embodiment, antenna 250 folds down during retrieval andstowage to reduce drag. It will be appreciated by those skilled in theart that an electro-mechanical device can be used to raise and fold thespring mounted antenna 250. Alternatively, a gimbaled antenna mount canbe used to maintain correct antenna position. Those skilled in the artwill appreciate that numerous other ways can be devised to keep antenna250 substantially vertical during surface tow.

FIG. 3 is a partial internal view of communications apparatus 110 inaccordance with an embodiment described herein. Center hull body 235 isat least partially hollow. Aft bulkhead 310 separates aft section 240from center hull body 235 and creates a watertight enclosure inside hullbody 235 for storage of electronics assembly 320. If desired, tow bodystructure 210 can optionally include a fore bulkhead that separates foresection 245 from center hull body 235. Particular embodiments mayoptionally fill the inside of hollow hull body 235, aft section 240, andfore section 245 with foam 550 to achieve positive buoyancy. Foresection 245 has a convex surface with a V-shaped upper edge 540 fordeflecting water as tow body 120 is towed on a water surface.

In accordance with an advantageous feature of the disclosed embodiment,the watertight chamber of center hull body 235 preferably encloses allelectronics required for communications apparatus 110 except for antenna250. Communications apparatus 110 may be rapidly integrated with manydifferent types of UUV systems since UUV systems need only be able tosend and receive data over standard Ethernet connection using standardinternet protocol (IP) network protocols.

Heat sink plate 300 is preferably composed of aluminum and weldedperpendicularly to aft bulkhead 310. Electronics assembly 320 is mountedon both sides of heat sink plate 300. Electronics assembly 320 isconnected to 802.11 antenna 250 and a watertight connector 330 for towcable 230. Alternatively, electronics assembly 320 may be potted insidehull body 235.

The present inventors have discovered that high signal attenuation,increased power Consumption, and difficulty in detecting when an antennahas reached the surface result from locating only the 802.11 and GPSantennas on tow body 120 such that the two antennas are connected toradio receivers onboard UUV 170 via a RF coaxial cable. Therefore, UUV170, preferably, incorporates a power over Ethernet module thatco-locates radio electronics and antennas for both 802.11 and GPSfrequency bands. Co-location of the radio electronics and antennasallows for a thin tow cable to be used for communications apparatus 110and minimizes signal attenuation from the use of tow cable 230.

Tow cable 230 transfers both power and data between tow body electronicsassembly 320 and UUV 170. The present inventors have found that using acoaxial cable to send RF signals to a surface antenna wouldsignificantly increase the overall weight of communications apparatus110. At low operational speeds, tow body 120 would be unable to lift aheavy cable, thereby increasing the likelihood of entanglement andsignificantly reducing the operational range of UUV 170. Thus, tow cable230 is preferably a fiber optic cable. Using a polypropylene jacket,fiber optic cable 230 can be made slightly buoyant, thereby, reducingthe possibility of cable entanglement. If UUV 170 is stationary, abuoyant fiber optic cable 230 can reach the surface if the deployedcable scope is greater than the depth.

FIGS. 4A and 4B are respectively a front view diagram and a bottom viewdiagram of an alternative embodiment of tow body 120 having ahydrodynamic boat hull shaped body structure 410. An optionalstabilizing side float 420 and at least one bridle attachment bar 220each having at least one bridle attachment point are mounted onto alifting wing 200 on either side of hull body 410. Lifting wing 200 iscentered on and mounted on top of hull body 410. Those skilled in theart will appreciate that electronic assembly 320 can also be mountedinside boat hull shaped body structure 410.

Another alternative embodiment of tow body 120 is illustrated in FIGS.5A and 5B, which respectively depicts front and bottom views of tow body120 having a hydrodynamic submarine shaped body structure 510. It willbe appreciated by those skilled in the art that tow body 120 can haveother alternative hydrodynamic and buoyant tow body structures.

While the embodiment of FIG. 3 is described with regard tomulti-sectional tow body 120 of FIG. 2, it will be appreciated by thoseskilled in the art that the tow bodies disclosed in FIGS. 4A, 5A, andother hydrodynamic tow bodies may be appropriately modified to embodythe principles of the invention described herein.

FIG. 6 is a schematic diagram of electronics assembly 320 in accordancewith an embodiment described herein. Electronics assembly 320 containsan embedded processor 650 that relays data to and from UUV 170 via fiberoptic cable 230. Embedded processor 650 contains an onboard 802.11 radioreceiver chip 660, RS232-level serial interface 670 for GPSconnectivity, 10/100 Ethernet LAN port 680 for tow cable 230, digitalinput/output 690, and sufficient CPU and memory for routing data at upto 54 Mbps between the Ethernet LAN port and the Wi-Fi interface ofantenna 250. Antenna 250 is connected to 802.11 transceiver 660 onboardembedded processor 650. In addition to the 802.11 and GPS antennas,embedded processor 650 can be configured to capture other types of data,such as, for example, images with an onboard camera. Electronicsassembly 320 also includes a float switch 610 connected to the digitalinput/output 690 of embedded processor 650, a DC power converter 630,and an Ethernet to fiber optic converter 640.

The example embodiment of FIG. 6 employs a Compulab CM-X270computer-on-module board with a PXA270ARM processor to meet all of theabove requirements, but other embedded processors that consume littlepower and space can be used. The Compulab CM-X270 board measures only66×44×7 mm and consumes 2W at maximum processor load.

An integrated GPS antenna and receiver module 620 is connected to aRS232-level serial interface 670. The integrated GPS antenna andreceiver module 620 can be, for example, Mighty GPS's all-in-oneBG-320RGT GPS module. The RS232-level serial interface 670 output isconnected directly to the CM-X270 serial port of embedded processor 650.Tow body structure 210 is made of a non-metallic material and, thus,will not interfere with satellite reception.

Embedded processor 650 preferably supports the open source embeddedLinux operating system, but any other operating system supported byembedded processor 650 may be used. The operating system on embeddedprocessor 650 runs at least three software modules that together providethe required functionality for communications apparatus 110.

First, the disclosed embodiment includes network layer packet routingsoftware to forward IP packets between UUV 170 and, for example, aremote surface receiver. The routing software should not buffer packetsdue to intermittent or slow wireless connections, for example, becausebuffering should be handled by a TCP control flow set up by UUV 170 orthe remote surface receiver.

Second, embedded processor 650 includes a software module for,supporting GPS navigation or other similar type platforms as known inthe art. This software module receives, parses and decodes serial GPSNMEA 0813 messages from integrated GPS antenna and receiver module 620.The decoded GPS information would be collected and sent periodically toUUV 170 as, for example, a TCP, UDP, XML, or CORBA message throughEthernet LAN port 680.

Third, embedded processor 650 includes a software module for supportingcommunications between UUV 170 and communications apparatus 110. Thissoftware module sends status information to and receives command andcontrol messages from UUV 170. Status information from embeddedprocessor 650 includes, for example, wireless signal strength, availablewireless networks, status of float switch 610 and GPS receiver 620, andother system information. Command messages from UUV 170 includes, forexample, control over the transmit power, configured wireless network,encryption parameters, and other network and system configurations.

If desired, an optional bi-directional RF amplifier 600 can be addedbetween antenna 250 and the onboard 802.11 radio receiver 620 to improvelink reliability and boost transmit power. The disclosed embodiment usesa 2.4 GHz bi-directional RF amplifier, such as, for example, the 2400CAE2.4 GHz bi-directional amplifier manufactured by RF Linx, which provides1 W of transmit power and 20 dB of receive gain. Amplifier 600 ispreferably mounted directly on heat sink plate 300 for improved heatdissipation.

In accordance with another illustrative feature of the disclosedembodiment, communications apparatus 110 has seawater coolingelectronics capability. Referring to FIG. 2, vent holes 260 in aft cone240 provide a constant supply of cooling water to heat sink plate 300.Electronics assembly 320 is ventilated with cooling water enteringthrough the vent holes 260 located on aft section 240 and exitingthrough keel slot 265 on the underside of aft section 240.Alternatively, if electronics assembly 320 is potted inside hull body235, amplifier 600 should be mounted at the lowest point of tow bodystructure 210 so that seawater can be used for heat dissipation.

FIG. 7A is a diagram of a reeling assembly 150 and FIG. 7B is a diagramof the reeling assembly 150 mounted inside UUV 170 in accordance with anembodiment described herein. Reeling assembly 150 includes a waterproofmotor housing 700 enclosing a direct current (DC) motor with an attachedspur gearbox (not shown), preferably having a 15:1 gear ratio, that ispowered by a waterproof cable connected to a power supply and controlswitch in UUV 170. Control switch directs the power to the motor tocontrol reeling tow body 120 in and out of tow body stowage area 160.Attached to the DC motor is a cable drum 710 large enough to accommodatethe length of tether 130. Cable drum 710 sits inside a reel frame. Ifdesired, a level wind can be mounted on cable drum 710 to prevent tether130 from jamming during reeling of tow body 120.

Reeling assembly 150 provides tension for holding stowed tow body 120inside UUV 170. If desired, an inner cover 740 which conforms to thebottom of tow body 120 can be mounted over reeling assembly 150 tostreamline the tow body stowage area 160 and, thereby reduce drag. Ahole in the cover 740 serves as a fairlead in directing tether 130 ontothe drum 710. Once tow body 120 has reached the surface, float switch610 of electronics assembly 320 is triggered to signal the DC motor tostop. High-speed communication to another vessel or shore platform andacquisition of GPS satellite data can then commence.

UUV 170 can provide all the power required to run electronics assembly320 except for a small battery that runs a clock inside electronicsassembly 320. Fiber optic cable 230 preferably contains two 24 AmericanWire Gauge (AWG) conductors for transporting power to tow body 120 fromUUV 170 and a fiber for transporting data. A single 24 gauge wireprovides almost 7 W of power at 12 V. The present inventors found thatelectronics assembly 320 would require approximately 2 W to 12 Wdepending on the RF amplifier used. If needed, additional power can beobtained by using a DC-DC converter 630 to step down the transmittedvoltage at tow body 120.

Referring to FIG. 1, tow body 120 can be lifted to the surface within aUUV operational speed ranging from stationary to approximately 5 knots.After deploying to the water surface, tow body 120 should sit high onthe water so that antenna 250 remains vertical and out of the water forbetter reception. Furthermore, tow body 120 must be stable at bothplaning and displacement speeds of up to approximately 5 knots for aprolonged period of time. The present inventors have discovered that theoptimal attack angle α for tow body 120, measured relative to the watersurface, is approximately 10 to 20 degrees. Tow body 120 can be towedsmoothly on the surface within this range for attack angle α.

Careful consideration must be given to selecting optimum location(s) toattach bridle(s) 270 to tow body 120 so that a sufficient lifting forceis created to lift tow body 120 to the surface and the attack angle α isapproximately 10 to 20 degrees when tow body 120 is pulled across thesurface. The bridle attachment point(s) can be located on bridleattachment bars 220, vertical stabilizer 255, or at other locationsincluding, for example, the tow body's 120 center of pressure and centerof buoyancy. The present inventors have discovered that a two-pointbridle attachment provided a stable configuration and low drag duringunderwater tow, surface tow, and transitions to and from the surface.The two bridle attachment points are located at the fore and aft ends ofbridle attachment bar 220 extending from the bottom of tow bodystructure 210. Alternatively, the aft end attachment point can belocated on vertical stabilizer 255 below the center of buoyancy, asshown in FIG. 2. By locating an attachment point on vertical stabilizer255, bridle 270 can be used to extend vertical stabilizer 255 duringdeployment of tow body 120. It will be appreciated by those skilled inthe art that other bridle attachment configurations may be employed,such as, for example, a single point attachment near the middle ofbridle attachment bar 220 extending from the bottom of tow bodystructure 210, or a three point bridle attachment in which twoattachment points are located on either fore corner of lifting wing 200and a third attachment point is located on vertical stabilizer 255 belowthe center of buoyancy.

The foregoing merely illustrate the principles of the invention.Although the invention may be used to particular advantage in thecontext of submerged vehicles, those skilled in the art will be able toincorporate the invention into other non-vehicle systems, such assubmerged platforms. It will thus be appreciated that those skilled inthe art will be able to devise numerous alternative arrangements that,while not shown or described herein, embody the principles of theinvention and thus are within its spirit and scope.

1-49. (canceled)
 50. An underwater vehicle comprising: an outer hullhaving a tow body stowage area; a communication apparatus capable ofbeing stored in the tow body stowage area and providing above thesurface communications, the apparatus comprising: a tow body tethered tothe underwater vehicle with a tether, the tow body comprising ahydrodynamic hull body including a top surface, wherein the top surfaceconforms to a portion of the outer hull of the underwater vehicle whenthe communications apparatus is stored in the tow body stowage area. 51.The underwater vehicle of claim 50, further comprising an electronicsassembly located inside the hydrodynamic hull body.
 52. The underwatervehicle of claim 51, wherein the electronics assembly includes aprocessor.
 53. The underwater vehicle of claim 51, wherein theelectronics assembly includes a wireless receiver.
 54. The underwatervehicle of claim 51, wherein the electronics assembly includes awireless transmitter.
 55. The underwater vehicle of claim 51, whereinthe electronics assembly includes a geo-location receiver.
 56. Theunderwater vehicle of claim 52, wherein the electronics assembly isventilated with cooling water entering through a plurality of ventholes.
 57. The underwater vehicle of claim 52, wherein the tethertransports power between the underwater vehicle and the electronicsassembly.
 58. The underwater vehicle of claim 52, wherein the tethertransports signals between the underwater vehicle and the processor. 59.The underwater vehicle of claim 50, wherein the communication apparatusfurther comprises an antenna mounted to the tow body.
 60. The underwatervehicle of claim 59, wherein the antenna is spring-loaded for keepingthe antenna substantially upright during surface tow and retractedduring stowage.
 61. The underwater vehicle of claim 50, wherein the towbody comprises a lifting wing for providing hydrodynamic lift to liftthe tow body from below the water surface to at least partially abovethe water surface.
 62. The underwater vehicle of claim 61, wherein thelifting wing has a curved upper surface.
 63. The underwater vehicle ofclaim 61, wherein the lifting wing extends at least an entire length andwidth of the hydrodynamic hull body of the tow body.
 64. The underwatervehicle of claim 50, wherein the tow body is towed at an attack anglebetween 10 to 20 degrees relative to the surface.
 65. The underwatervehicle of claim 50, wherein the tow body comprises a verticalstabilizer projecting from a keel slot located on the hull body.